It has been known for many years in the design of passenger doors for motor vehicles to employ an outer panel which is structural and has an aesthetic outboard surface. Most frequently, such structural outer panels are stamped sheet steel or molded engineering plastic having a painted outboard surface. Thus, the outer panel or outer door panel provides both a decorative outer surface for the motor vehicle body and makes significant structural contribution to the vehicle door and to the vehicle body as a whole. The outer panel typically is concave to the inside of the vehicle so as to define a door cavity along with other structural door components, such as fore-and-aft end panels or the like. Motor vehicle doors also have an inner panel, that is, a structural or semi-structural panel sometimes formed of one or more flat or contoured cross-beams, such that considerable open space and/or defined openings exist approximately in the plane of the inner panel. Thus, in known designs the door cavity is defined generally between the outer panel and the inner panel. Typically, openings are provided in the inner panel for components of various functional hardware positioned in the door cavity and mounted to the inner panel.
For aesthetic reasons, a decorative trim panel formed of fiberboard, sheet plastic or the like, is mounted to the inboard side of the vehicle door, overlaying the inner panel. Such trim panels are generally non-structural, since they perform primarily a decorative purpose and serve to separate vehicle occupants from the moving parts, grease, etc. of hardware componentry within the door cavity. Certain componentry typically extends from the door cavity, through the trim panel, into the passenger compartment. Thus, the trim panel, while non-structural, must be sufficiently rigid and robust to withstand occupant contact and the like, and for mounting of various switches, cover plates, door pulls, etc. Trim panels also must have dimensional stability over the expected operating temperature range of a motor vehicle passenger compartment, and must be suitable to act as a supporting substrate surface for an overlying decorative web, for example, carpeting, vinyl sheet, fabric, etc.
Considerable design complexity and cost is associated with the manufacture and assembly of vehicle doors, especially in view of their use of an outer panel, an inner panel and a trim panel. The complexity and costly precision required of vehicle doors which are assembled of outer panels, inner panels and trim panels is reflected in the teaching of U.S. Pat. No. 5,367,832 to Compeau et al, entitled Tubular Plastic Mounting Panel for Door Hardware. A one-piece plastic molded member is suggested there, adapted to mount a window regulator and optionally other functional hardware. Various snap fasteners are integrally molded with the mounting panel for snap-together fastening of various door hardware, such as the window regulator, window regulator motor, door handle, and door latch control rods. Such molded plastic member is adapted to be mounted into a door cavity; a decorative trim panel would be used in the usual fashion to provide an aesthetic inboard finish. Others have taught a post-assembly coupling system for a window regulator or other vehicle door hardware to reduce assembly difficulty. In U.S. Pat. No. 4,766,697 to Boileau, for example, it is noted that assembly problems have hampered the development of modular door panel assemblies which would include window regulators preassembled to an interior trim panel. A snap-coupling is suggested, whereby certain window regulator componentry could be mounted to the outboard surface of a trim panel to reduce assembly complexity. Upon attaching the trim panel to the inner door panel, the window regulator would snap-connect to other window regulator componentry already attached to a windowpane which has been preassembled into the vehicle door cavity.
It is an object of the present invention to provide motor vehicle door components and assembly techniques having reduced complexity and/or improved performance characteristics. It is a further object of at least certain preferred embodiments to provide such door components and assembly techniques which are compatible with current motor vehicle assembly constraints, and suitable for meeting the demands of the harsh motor vehicle use environment. Additional objects will be apparent from the following disclosure of the present invention and detailed discussion of preferred embodiments.